Preheat your oven to 350°F (175°C). If using a dark-coated pan, reduce the temperature to 325°F (160°C).
Lightly grease a 9x5-inch loaf pan. For easy removal, line the bottom with parchment paper, leaving overhangs on the long sides.
In a large bowl, combine the mashed bananas, granulated sugar, brown sugar, butter or oil, sour cream, peanut butter, eggs, and vanilla extract. Whisk until everything is well blended.
Gently stir in the flour, baking soda, salt, and chocolate chips (if using). Mix until just combined and no dry streaks remain—be careful not to overmix.
Pour the batter into the prepared loaf pan and spread it evenly.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs (but no wet batter).
Let the bread cool in the pan for 10–15 minutes.
Carefully lift it out using the parchment paper overhangs and transfer it to a cooling rack to cool completely. The peanut butter flavor is best when the bread is fully cooled—or even the next day!